The present invention is concerned with a vehicle roof for a motor vehicle, having a roof part which can be moved in the longitudinal direction of the vehicle and can be adjusted between a closed position closing a roof opening in the motor vehicle, and an open position releasing the roof opening and having a motorized drive having at least one driving pinion for driving two driving cables which adjust the roof part and are guided along both sides of the roof opening.
A vehicle roof of this type is disclosed in DE 33 16 739 C2. A driving unit for a vehicle roof has a plurality of adjustable roof segments which are arranged one behind another in the longitudinal direction of the vehicle and in the closed position close a roof opening, and in the open position are pushed together or moved into the upright position, so that the roof opening is released. For the transfer between the closed position and open position a driving motor having a driving pinion is provided to drive two driving cables which are stiff in terms of compression and are connected to the segments. The driving motor and the driving pinion are arranged in the region of the front side of the roof opening, the driving pinion acting simultaneously on both driving cables.
The driving unit consisting of the driving motor and the driving pinion in the region of the roof front side has to be of small construction because of the restricted spatial conditions, in particular because of the small roof thickness; otherwise, fittings obstructing the interior of the vehicle are required. On the other hand, the driving motor has to have sufficiently high power available so that the increased friction on account of the plurality of individual movable segments can be overcome, and the vehicle roof can be opened and closed reliably. However, the motor power needed can only be provided by means of a motor of sufficient size.
According to DE 33 16 739 C2, the conflict between the size of the motor and motor power is resolved by a large driving motor, but this restricts the space in the vehicle interior, in particular the headroom.
DE-AS 25 08 106 discloses a drive for a motor vehicle roof, which comprises two driving cables on the two sides of an adjustable roof portion. The driving cables are each driven by a driving pinion, which in turn is driven by a drive shaft of a common drive motor. The drive motor is arranged in the center of the vehicle roof. The two drive shafts bridge the distance between the roof center and the roof side, along which the respective driving cable with the driving pinion extends. Since a drive shaft each extends to the left and to the right side of the roof, it is necessary for reasons of symmetry to place the drive motor precisely in the roof center. This limits the design options for the drive of the roof part. Furthermore, care must be taken that the drive motor, which is arranged in the area of the vehicle roof that is fixed to the body immediately adjacent to the wind shield frame, does not collide with the sealing devices on the vehicle roof.
An object of the present invention is to overcome the problem of specifying a drive for a vehicle roof, with a drive having good operational reliability and providing sufficiently high power, yet at the same time, being of small construction.
According to the invention, this problem is solved by assigning driving cables to a respective motor-operated driving pinion.
According to the invention, provision is now made for each of the two driving cables, via which the roof part is adjusted at its two end sides between an open and closed position, in each case to be acted upon by a driven driving pinion. This makes it possible to position the driving pinions at different locations and to take design and structural conditions into consideration. The division into two driving pinions means that the position of the driving pinions can be varied to a greater extent than in the prior art and that a flexible construction can be achieved.
According to a first advantageous configuration, provision is made for the two driving cables to be driven via a common driving motor which acts directly or indirectly on two driving pinions. In this embodiment, a first driving pinion drives one of the two driving cables, and the second driving pinion is situated between the driving cables and transmits the driving movement from the first to the second driving cable. This configuration has the advantage that only one motor is needed for driving both cables and yet each cable is assigned a driving source, as a result of which delays in the drive, due to elastic or plastic behavior of the driving cables, are avoided. A further advantage resides in the fact that the driving movement of the two cables is synchronized automatically via the driving pinion situated between the two cables.
The two driving pinions can be positioned on different sides of the roof opening, the first driving pinion, which is driven directly by the motor, advantageously being arranged in the lateral region of the roof opening, and the second driving pinion advantageously being arranged in the region of the front side of the roof opening where the two driving cables advantageously overlap. In principle, the driving motor may be placed in the lateral region over the entire length of the roof opening, but optionally also in the region of the front edge or of the rear side of the roof opening.
According to a second advantageous embodiment, two driving motors each having a driving pinion are provided, each driving cable being assigned a respective driving motor having a driving pinion. Since the overall power to be produced is distributed to a plurality of motors, the motors can be sized smaller to reduce the space required for each motor. On the other hand, however, higher power values may also be achieved because of the plurality of motors. A further advantage of this configuration resides in the fact that the driving forces acting on each cable are reduced because each cable is driven directly by the motor assigned to it and the power requirement is orientated to only one cable to be driven. The reduced driving forces increase the service life of the device and make it possible to use components which are of a lesser size and are more cost-effective. In addition, through the use of identical parts, in particular driving motors and pinions of identical construction, simplifications in terms of design and reductions in costs are achieved.
It may optionally be appropriate to provide more than two driving motors having a corresponding number of driving pinions.
In a preferred development of the embodiment having two driving motors, a synchronizing pinion is provided between the two driving cables. The pinion has the task of synchronizing the movement between the two cables in order to prevent differences in speed in the cables and the risk of twisting in the cables, and sloping position or tilting of the roof part. The synchronizing pinion is expediently arranged in the region of the front side of the roof opening, in particular in the center of the front side.
The roof part is expediently of multipart configuration and consists in particular of a plurality of individual segments which are arranged one behind the other, are acted upon by the driving cables and are adjusted between the open and closed position.
The driving motors are both advantageously arranged either in the lateral region or in the region of the front side, in particular mirror-symmetrically with respect to a longitudinal central plane of the vehicle, in order to achieve a uniform distribution of force over the length of the driving cables.